'Mixing number' of permutations

Hugo Pfoertner all at abouthugo.de
Thu Aug 17 14:29:59 CEST 2006


SeqFans,

today Hauke Reddmann started a new thread in the NG sci.math

http://groups.google.com/group/sci.math/msg/b1c1164b936c6dca

<<
For easyness, I use the data of my lest chess tournament :-)
The finish in terms of the starting numbers was
7 1 6 4 3 8 5 2|9|10|14 15 20 13 18 16 23 22 12 26 11 17 19 27 25 21
24|28

A | marks boundaries between consecutive number subsets that permute
to themselves. Note that I (the 16) also permute to myself, but there
are number crossing from both sides and so this is no boundary.

Obvious question: How many boundaries occur in a random permutation?
Clearly a tournament is about the opposite of random, as the swap
numbers will be low.

Example n=3

1|2|3
1|3 2
2 1|3
2 3 1
3 1 2
3 2 1
-- 
Hauke Reddmann <:-EX8    fc3a501 at uni-hamburg.de
His-Ala-Sec-Lys-Glu Arg-Glu-Asp-Asp-Met-Ala-Asn-Asn
>>

Is there anything in the OEIS that can answer his question? Any other
ideas?

Can you please CC answers also to Hauke; AFAIK he is not member of the
Seqfan community.

Hugo Pfoertner






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